Mechanisms of IgE mediated FceRI regulation

S摘要：IgE/FceRI网络是过敏反应的中枢 炎症本身可能参与了支气管的发生。 高反应性和哮喘。FceRI表面表达水平为 受控于循环免疫球蛋白E水平。这项规定有很大的影响 生理意义，因为FceRI表达增加会转化为 增强的效应器功能。此外，最近的抗IgE临床试验已经 强调了这一规定的重要性，显示嗜碱性粒细胞减少 效应器功能与相应的FceRI表达降低。然而， 目前尚不清楚IgE如何调节FceRI的表达。我们建议进一步 从以下四个方面认识IgE介导的FceRI调节 目标。具体目标1：研究IgE介导的FceRI上调的过程。 在这一目标中，我们将剖析IgE介导的过程 上调FceRI，确定相关机制(S)。具体目标2： 经典β蛋白对IgE介导的FceRL上调的影响 在这个目标中，我们将跟踪我们的初步数据，显示IgE介导 Alphagamma2组FceRI上调幅度明显大于Alpha组 体外表达β-Gamma2的细胞。我们将确定分子 这种差异背后的机制(S)。我们还将分析 Alphagamma2与Alphabetagamma2表达上调的生理学意义 老鼠。最后，我们将确定贝塔基因中已知的多态 对IgE介导的FceRI上调有影响。具体目标3：澄清 新的β基因产物对免疫球蛋白E介导的血管内皮生长因子上调的影响 我们的初步数据显示，人类的β基因产生了两个 共同表达并编码两种蛋白质的可选转录本 相反的功能：经典的贝塔，和一种新描述的截短蛋白质， 贝塔。我们将确定BetaT是否影响IgE介导的调节。我们会 还要评估产生BetaT的替代剪接是否受到 免疫球蛋白介导的调控。最后，我们将确定是否知道 β基因的多态会影响β基因的选择性剪接。 具体目标4：剖析FceRI所需的最小结构 免疫球蛋白介导的调控。确定了分子机制(S) 在IgE介导的FcERI调节下，我们将确定最小 这些机制的结构基础。我们会鉴定出氨基酸 阿尔法链中的序列，通过以下方式介导上调 使用一些突变和嵌合的受体。此外，我们还将 确定伽马是否会影响使用类似策略的上调。 最后，我们将验证上调监管所需的关键域 影响目标1中揭示的IgE介导的FceRI上调的机制(S)。 综上所述，这些分析将为 控制免疫球蛋白E介导的调节的过程和分子参数 FceRI表达。

(Applicant?s Abstract) The IgE/FceRI network is central to allergic inflammation and as such may be involved in the genesis of bronchial hyperresponsiveness and asthma. The level of FceRI surface expression is controlled by the level of circulating IgE. This regulation has great physiological significance since increased FceRI expression translates into enhanced effector function. Furthermore, recent anti-IgE clinical trails have underscored the importance of this regulation, showing decreased basophil effector function with corresponding decreased FceRI expression. However, nothing is known of how IgE regulates FceRI expression. We propose to further the understanding of IgE-mediated FceRI regulation through the four following aims. Specific Aim 1: Characterize the process of IgE-mediated FceRI up-regulation. In this aim we will dissect the process of IgE-mediated up-regulation of FceRI, determining the mechanism(s) involved. Specific Aim 2: Elucidate the impact of classical beta on IgE-mediated up-regulation of FceRL In this aim, we will follow-up on our preliminary data that show IgE-mediated up-regulation of FceRI is significantly greater in alphagamma2 than in alpha beta gamma2 expressing cells in vitro. We will determine the molecular mechanism(s) that underlie this difference. We will also analyze the physiolgical significance of alphagamma2 vs. alphabetagamma2 up-regulation in mice. Finally, we will determine whether known polymorphisms in the beta gene have an impact on IgE-mediated FceRI up-regulation. Specific Aim 3: Elucidate the impact of a new product of the beta gene on IgE-mediated up-regulation of FceRL Our preliminary data show that the human beta gene gives rise to two alternative transcripts that are co-expressed and encode two proteins with opposing functions: classical beta, and a newly described truncated protein, betaT. We will determine if betaT impacts IgE- mediated regulation. We will also assess if the alternative splicing to produce betaT is affected by the IgE-mediated regulation. Finally, we will ascertain whether known polymorphisms in the beta gene affect the alternative splicing of beta. Specific Aim 4: Dissect the minimal structure of FceRI required for IgE-mediated regulation. Having identified the molecular mechanism(s) that underlie IgE-mediated regulation of FcERI, we will determine the minimal structural basis for these mechanisms. We will identify the amino acid sequences in the alpha chain that are necessary to mediate up-regulation by using a number of mutated and chimeric receptors. In addition, we will determine if gamma impacts up-regulation utilizing a similar strategy. Finally, we will verify that the critical domains required for up-regulation affect the mechanism(s) of IgE-mediated FceRI up-regulation revealed in Aim 1. Taken together, these analyses will provide significant insights into the process and molecular parameters that control the IgE-mediated regulation of FceRI expression.